Plant growth control by use of ethers of chlorinated and fluorinated phenols



PLANT GROWTH CONTROL BY USE OF 'ETHERS OF CHLORINATED AND FLUO- RINATED PHENOLS William L. Howard, Stanley R. McLane, and Robert L. Weintraub, Frederick, Md., assignors to the United States of America as represented by the Secretary of the Army No Drawing. Original application Oct. 29, 1954, Ser. No. 465,765, now Patent No. 2,839,582, dated June 17, 1958. Divided and this application Feb. 13, 1958, Ser. No. 718,107

2 Claims. (Cl. 712.3) (Granted under Title '35, US. Code (1952), see. 266) ing as herbicides and also in the production of sterility.

They may also be employed to prevent premature drop of fruit.

The ethers which we have found to be efiective have straight alkyl chains containing even numbers of carbon atoms. They are further characterized as follows:

Aliphatic chain,

Phenolic group: carbon atoms 4-chlorophenyl 8 to 18. 2,4-dichlorophenyl 8 to 18. 2,4,5-trichlorophenyl 16. 4-fiuorophenyl 12, 14 and 16. 2,4-difluorophenyl a 12, 14 and 16. 2-methyl-4-fluorophenyl 12, 14 and 16.

Of these compounds, the group consisting of 4-chloro phenyl myristyl ether, 2,4-dichlorophenyl myristyl ether and 2,4-dichlorophenyl cetyl ether have outstanding activity. 2,4-dichlorophenyl myristyl ether is the most active of all. r

In comparison to the well known herbicide 2,4-dichlorophenoxy acetic acid (2,4-D), these compounds possess distinctive properties in that they give a delayed action which is spread over a long period of time, giving a greater over all effect when used in herbicidal quantities. When used in sub-lethal quantities the action, as in pro duction of seedless fruit, is more gradual and produces fewer objectionable side effects. As herbicides, the ethers are applied in the same manner as, but are less active than 2,4-D. Due to their low solubility in water, they are preferably emulsified by the use of suitable emulsifying agents. Since they have densities near that of water they produce stable emulsions. They may also be used as solutions in alcohols, glycol ethers, etc. Other growth regulating properties are illustrated by the following experiments:

EXAMPLE I Field grown tomato, pepper, squash, and eggplant plants were sprayed with 2,4-dicblorophenyl tetradecyl This application is a division of applica- 2,937,935 Patented May 24, 1960 ether at rates of 0.1 and 0.5 pound per acre. Seedless fruit was produced in each'case. The seedless tomatoes were quite firm and were not as puffy as some seedless fruit. Tomato yields were not reduced. The eggplant was normal both in form and in yield. Pepper yields were not reduced but the fruit was flattened and not of normal shape. Squash was of abnormal shape.

EXAMPLE II number of carbon atoms in a straight alkyl chain containing from eight to eighteen carbon atoms, 2,4,S-trichlorophenyl n-hexadecyl ether, 4-fluorophenyl n-dodecyl ether, 4-fluorophenyl n-tetradecyl ether, 2,4-difluorophenyl ndodecyl ether, and the n-dodecyl, n-tetradecyl, and nhexadecyl ethers of 2-methyl-4-iluorophenol. The new ethers are oils or crystalline solids somewhat soluble in many organic solvents such as hydrocarbons, alcohols, ethers, ketones, etc., and practically insoluble in water. They are stable to light, air, and carbon dioxide, and have low volatilities. They are useful in the control of the growth of plants, as described above, and as intermediates in the preparation of more complex organic derivatives.

The compounds may be prepared by reacting (l) at least a molecular proportion of the proper chlorinated or fluorinated phenol as the sodium salt thereof and (2) a molecular proportion of an alkyl halide such as octyl chloride, myristyl bromide, cetyl bromide,' etc., or any similar halogenated derivative of an alkane bearing the desired alkyl group carbon atoms. The reaction is carried out in the presence of a solvent such as absolute ethanol. A catalyst such as sodium or potassium iodide may be used to facilitate halogen interchange and increase the yield of the ether by preventing dehydrohalogenation of the alkyl halide to the corresponding alkene.

In the preferred method of preparation, the sodium is dissolved in absolute ethanol and an equivalent amount of the phenol is added to form the sodium phenolate. Potassium iodide is then added and dissolved, followed by an equimolecular amount of the alkyl halide. The mixture is then refluxed for 12 hours or longer. The reaction mixture is diluted with water and the ether separates out. The aqueous-alcoholic layer is extracted with a suitable solvent, the extract combined with the precipitated ether and the resulting solution washed with aqueous alkali to remove unreacted phenol and then with water to remove residual salts and alkali. After drying the extract, the solvent is evaporated, leaving behind a liquid or solid ether which can be purified by distillation at reduced pressure or recrystallized from a suitable medium, as dictated by its physical properties.

As an illustration of the method of preparation, the production of myristyl 2,4-dichlorophenyl ether will be described. As has been previously pointed out, this compound is the most active for our purposes of all of the compounds of our group. The other ethers are prepared in a similar manner.

EXAMPLE III 10.2 grams of 2,4-dichlorophenol was dissolved in 20 milliliters of absolute ethanol. To this was added a solution of 1.4 grams of sodium metal dissolved in 60 milliliters of absolute ethanol. A solution of 9.0 grams of potassium iodide in 120 milliliters of absolute ethanol was added and the mixture refluxed 15 minutes. 20 grams of myristyl bromide was then added and the resulting mixture refluxed 36 hours on a steam bath.

After cooling the reaction mixture it was diluted with 500 milliliters of water, then extracted with 300 milliliters of ethyl ether in 100 milliliter portions. The ether extract was separated and washed with 100 milliliters of 5% sodium hydroxide solution, then 300 milliliters of water, again separated and dried over anhydrous sodium sulfate.

The ethyl ether was removed by distillation leaving 4 We claim:

. 1. A method of controlling the growth of plants which comprises applying to the plants a small quantity of a compound selected from the group consisting of: the noctyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl and n-octadecyl ethers of 4-chlorophenol and of 2,4-dichlorophenol; the n-hexadecyl ether of 2,4,5-trichlorophenol; the n-dodecy-l, n-tetradecyl and n-hexadecyl ethers of 4- fluorophenol; the dodecy'l, n-tetradecyl and n-hexadecyl ethers of 2,4-difluorophenol; and the n-dodecyl, n-tetradecyl and n-hexadecyl ethers of 2-methy1-4-fluorophenol.

2. A method of controlling the growth of plants comprising applying to the plants a small amount of 2,4- dichlorophenyl myristyl ether.

behind a solid which was crystallized from any suitable solvent, such as ether or ligroine giving white crystals of References Cited in the fil of this patent 2,4-dichlorophenyl myristyl ether melting at 33-34 C., and having carbon and hydrogen contents of 66.56% and UNITED STATES PATENTS 8.85% respectively. For C H Cl O the theoretical 2,327,338 Carswell Aug. 24, 1943 values are 66.84% and 8.98% respectively. 20 2,712,990 Swezey July 12, 1955 Representative ethers of our group that have been pre- 2,712,991 Swezey July 12, 1955 pared by the method described above, and the reactants 2,714,063 Swezey July 26, I955 employed, are shown in Table I. 2,777,762 Toornman J an. 15, 1957 Table l Reaetants Boiling Point Melting Ether Product Point, [ane Density,

, 0. Temp, Pressure, C. Alkyl Halide Phenol 0. mm. Hg

abs.

n Octyl bromide 2,4 diehlorophenol n Octyl 2,4 diohlorophenyl ether p n Deeyl brornide do .1 n Deeyl 2,4 dichlorophenyl ether Lauryl bromide Oetadeoyl b1 omlde do Oetadecyl 2,4 dichlorophenyl ether Cetyl bromide. 2,4,5 trichloropheno Getyl 2,4,5 triehlorophenyl ether- Lauryl bromide 4 fluorophenol Lauryl 4 fiuorophenyl ether.-.

Myristyl bromide. d Myristyl 4 fluorophenyl ether- Oetyl bromide Cetyl 4 fluorophenyl ether Lauryl bromide Lauryl 2,4 di luorophenyl ether. Myristyl bromide Myristyl 2,4 difiuoropheuyl ether-.

Get brom' e- Oetyl 2,4 difiuorophenyl ether Lauryl bromide. Lauryl 2 methyl 4 fluorophenyl ethe Myristyl bromide Myristyl 2 methyl 4 fluoropheuyl ether Oetyl bromide Cetyl 2 methyl 4 fluorophenyl ether Lauryl 2,4 dichlorophenyl ether Myristyl 2,4 diehlorophenyl ether. a-.- Cetyl 2,4 dichlorophenyl ether While we have described our compounds, their properties and their use in considerable detail, it will be understood that a number of variations are possible. We therefore desire our invention to be limited solely by the scope of the appended claims.

OTHER REFERENCES Aberg: Chemical Abstracts, vol. 47, col. 5497(b), 1953.

McLane et a l. in Weeds, October 1953, p. 288-291. 

1. A METHOD OF CONTROLLING THE GROWTH OF PLANTS WHICH COMPRISES APPLYING TO THE PLANTS A SMALL QUANTITY OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF: THE NOCTYL, N-DECYL, N-DODECYL, N-TETRADECYL, N-HEXADECYL AND N-OCTADECYL ETHERS OF 4-CHLOROPHENOL AND OF 2,4-DICHLOROPHENOL, THE N-HEXADECYL ETHER OF 2,4,5-TRICHLOROPHENOL, THE N-DODECYL, N-TETRADECYL AND N-HEXADECYL ETHERS OF 4FLUOROPHENOL, THE DODECYL, N-TETRADECYL AND N-HEXADECYL ETHERS OF 2,4-DIFLUOROPHENOL, AND THE N-DODECYL, N-TETRADECYL AND N-HEXADECYL ETHERS OF 2-METHYL-4-FLUORROPHENOL. 